The central canal, as well as the entire ventricular system of which it is a part, is lined with ependyma, a specialized form of epithelium with neurological cells. The central canal or ependymal canal runs longitudinally through the length of the spinal cord and contains cerebrospinal fluid.
Epithelium is a specialized tissue that lines the insides of surfaces and cavities in the body and does not contain blood vessels.The ependyma is made up of ependyma cells, which produce cerebrospinal fluid in the choroid plexus but not in the central canal. Ependyma cells are ciliated simple columnar. The cilia that line the ependymal cell surfaces circulate cerebrospinal fluid throughout the central canal and the central nervous system. Microvilli also cover their surfaces and absorb cerebrospinal fluid.
Fluid release across the ependyma is controlled by tight, modified junctions between ependymal cells. This fluid release allows for the exchange of cerebrospinal fluid between the ventricular system and the neurological tissues of the brain and spinal cord. The basal membrane of ependyma cells has tentacle-like extensions attaching to astrocytes, a form of neurological cell. Cerebrospinal fluid protects and cushions the brain and spinal cord and helps maintain proper neurological blood flow. It is 99 percent water and contains plasma proteins.